Here’s a snapshot of the memory of a running live cd of Ubuntu. I ran a script to load 0123456789abcdef over and over and it’s clearly readable. Nothing special is required for this, as the Hypervisor has access to anything that the VM does. If the VM loads the encryption key for your disk into memory it will be available to the provider.
Sadly, most of the ones I’ve found are too complicated, and getting all devices to accept the CA is more hassle than it’s worth for self hosting. I’ve given up and just buy my wildcard cert for 60$/yr and just put it on everything.